Genesis 4:14 New International Version (NIV)
14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me.”
So far in Genesis, we have read about four people. We read about Adam and Eve. Then we read about Cain and Abel. Where are all the other people? Why was Cain worried about being killed by someone else? Then, he gets a wife, and where did she come from? In fact, Adam and Eve had several children because they had been told in Genesis 1:28, ‘fill the earth’. The wife Cain chose may have been one of his sisters or a niece. At this time, the human race was still pure genetically, and there were no side effects of marrying relatives. Cain’s guilt and fear weighed heavy on him, and he feared backlash from his family. He knew if he was capable of murder, they were too.